Cyclone, hurricane, typhoon: What’s the difference?

As Cyclone Vayu rages in
the Indian ocean^[1], you may be wondering
what a cyclone even is. But if you’ve ever survived a hurricane or
typhoon, you already know the answer.

In the Atlantic and northern Pacific, the storms are called
“hurricanes,” after the Caribbean god of evil, named Hurrican.

In the northwestern Pacific, the same powerful storms are called
“typhoons.” In the southeastern Indian Ocean and southwestern
Pacific, they are called “severe tropical cyclones.”

In the northern Indian Ocean, they’re called “severe cyclonic
storms.” In the southwestern Indian Ocean, they’re just “tropical
cyclones.”

To be classified as a hurricane, typhoon, or cyclone, a storm
must reach wind speeds of at least 74 miles per hour (119
kilometers per hour).

If a hurricane’s winds reach speeds of 111 miles per hour (179
kilometers per hour), it is upgraded to an “intense hurricane.”

If a typhoon hits 150 miles per hour (241 kilometers per hour)
then it becomes a “supertyphoon.”

While the Atlantic hurricane season runs from June 1 through
November 30, the typhoon and cyclone seasons follow slightly
different patterns.

In the northeastern Pacific, the official season runs from May
15 to November 30. In the northwestern Pacific, typhoons are most
common from late June through December. And the northern Indian
Ocean sees cyclones from April to December.

Whatever you choose call them, these monster storms are powerful
natural events with the capacity to wreak some serious havoc.

According to NOAA’s
National Hurricane Center^[2], the average hurricane
eye—the still center where pressure is lowest and air temperature
is highest—stretches 30 miles (48 kilometers) across, with some
growing as large as 120 miles (200 kilometers) wide.

The strongest storms, equivalent to Category 5 on the Saffir-Simpson
scale^[3], have sustained winds
that exceed 155 miles per hour (250 kilometers per hour).

With the aid of satellites and computer models, such storms can
be predicted several days in advance and are relatively easy to
track.^[4] But as Hurricane Sandy
showed recently, predicting the path that a hurricane or typhoon or
cyclone will take after it’s formed is still
tricky^[5].

Effects of global warming?

In theory, warmer atmospheric temperatures should lead to warmer
sea surface temperatures, which should in turn support stronger
hurricanes.

The number of Category 4 and 5 hurricanes worldwide nearly
doubled from the early 1970s to the early 2000s. Moreover, both the
duration of tropical cyclones and their strongest wind speeds have
increased by about 50 percent over the past 50 years.

“Average tropical cyclone maximum wind speed is likely to
increase, although increases may not occur in all ocean basins,” an
Intergovernmental Panel on Climate Change report noted.

It is often difficult to assess the impact of a warming planet
on any individual storm, but increasing computing power and more
sophisticated weather modelling is allowing
the science to progress^[6].